Coin analyzer sensor configuration and system

Abstract

A coin analyzer system includes a coin detecting sensor having a body defined by a magnetic core with spaced apart sides to define there-between an air gap that is large enough to position any size coin which may be deposited. A coil that is magnetically coupled to the core generates a uniform magnetic flux through the air gap from one side to the other so that the positioning of the coin in the air gap is not critical. A return path is provided in the core for returning the magnetic flux to the one side from the other side and thereby completing the magnetic circuit. The arms surrounding the coin sensing region define facing surfaces which converge outwardly from the bite portion in order to produce a uniform magnetic circuit reluctance for all portions of the facing surfaces. The core may be divided into two core portions separated by a secondary air gap in the return path with a pair of coils provided, one magnetically coupled with each of the core portions. One coil may serve as a transmitting coil and the other as a receiving coil. Various detection circuits are disclosed for connection with the sensor coils in order to determine the denomination of the test coin.

The embodiments of the invention in which an exclusive property of privilege is claimed are defined as follows: 
     
       1. A coin detecting sensor comprising: a generally C-shaped core of ferro-magnetic material including a bight portion and a pair of spaced apart arms extending in a same direction frown said bight portion, defining a coin sensing primary air gap between said arms, said core being divided into two core portions separated by a secondary air gap; and   a pair of coils, one magnetically coupled with each of said core portions to generate and sense a magnetic flux in said core and across said air gaps when one of said coils is excited with electrical energy.   
     
     
       2. The sensor in claim 1 wherein said ferro-magnetic material has high permeability. 
     
     
       3. The sensor in claim 2 wherein said permeability is at least approximately 2000. 
     
     
       4. The sensor in claim 1 wherein said arms terminate in facing surfaces defining said primary air gap, said facing surfaces being defined by facing surface portions that are spaced apart a distance predetermined to establish a uniform magnetic circuit reluctance at all portions of said primary air gap. 
     
     
       5. The sensor in claim 4 wherein said facing surfaces converge outwardly from a central portion of said body. 
     
     
       6. A coin detecting sensor comprising: a generally E-shaped core of ferro-magnetic material including at least one base member and three arms extending in a same direction from said base members and spaced apart in order to define a test coin sensing region between two adjacent ones of said arms and a sample coin sensing region between two other adjacent ones of said arms;   a coil magnetically coupled with said base member between said two adjacent ones of said arms; and   another coil magnetically coupled with said base member between said two other adjacent ones of said arms.   
     
     
       7. The sensor in claim 6 wherein said including means defining air gap in said base member between said two adjacent ones of said arms and means defining another air gap in said base member between said two other adjacent ones of said arms. 
     
     
       8. The sensor in claim 7 including means for adjusting the reluctance of said air gaps. 
     
     
       9. A coin detecting system comprising: at least two sensor units, each sensor unit including a body having spaced apart sides defining an air gap in said body and a flux return path in said body for magnetic flux from one of said sides to the other of said sides, said air gap having a width larger than the diameter of a coin in order to accommodate a coin in said air gap;   a positioning device for positioning a sample coin in said air gap of one of said sensor units and a test coin path through said air gap of another one of said sensor units; and   an electronic control that is responsive to said magnetic flux in said at least two sensor units when a sample coin is in said air gap of one of said sensor units and a test coin is in said test coin path, said electronic control including a plurality of induction devices one magnetically coupled with each of said sensor units, an excitation generator for electrically exciting said induction devices in order to generate a magnetic flux in each sensor unit body from one of said sides to the other of said sides through said air gap, and a detection system for comparing an electrical signal produced by said induction devices to determine if a test coin in said test coin path is the same as a sample coin in said positioning device, wherein each of said induction device is a pair of inductors magnetically coupled with the associated sensor unit, said excitation generator applies a current to one of said pair of inductors and wherein said electrical signal is induced in the other one of said pair of inductors.   
     
     
       10. The system in claim 9 wherein said body of each sensor unit is divided into separated body portions and wherein each of said pair of inductors of the associated induction device is magnetically coupled with one of said body portions. 
     
     
       11. The system in claim 10 wherein said body portions of each sensor unit are separated by another air gap. 
     
     
       12. The sensor in claim 9 wherein said body of each sensor is made from a ferro-magnetic material. 
     
     
       13. The sensor in claim 12 wherein said ferro-magnetic material has high permeability. 
     
     
       14. The sensor in claim 13 wherein said permeability is at least approximately 2000. 
     
     
       15. A coin detection system comprising: a sample coin sensor unit adapted to generating and sensing a first magnetic field and means for positioning a sample coin in said first magnetic field;   a test coin sensor unit adapted to generating and sensing a second magnetic field and means for positioning a test coin in said second magnetic field;   a comparison circuit responsive to said sample coin sensor unit and said test coin sensor unit and adapted to comparing the intensity of said first and second magnetic fields when a sample coin is in said first magnetic field and a test coin is in said second magnetic field, wherein said comparison circuit produces an output indicative of the intensities of said first and second magnetic fields; and   a detection circuit responsive to said comparison circuit output including a differential amplifier having an output, a first input connected with said output of said comparison circuit and a first reference voltage, a feedback path between said output and said first input, a second input connected with a second reference voltage and a reset input, whereby said feedback path latches said detection circuit output in one of two output states and said reset input resets said detector circuit output to the other of said two output states.   
     
     
       16. The system in claim 15 including means for applying a bias voltage to said comparison circuit output and wherein said reference voltage is proportional to said bias voltage. 
     
     
       17. The system in claim 15 including a rectifier circuit connected with said first input by a diode, said rectifier circuit including another diode, wherein said diode and said another diode are connected in series in opposite polarity with each other. 
     
     
       18. The system in claim 15 including a coin confirmation sensor connected with said reset input, said coin confirmation sensor responsive to a coin being deposited in a coin receptacle. 
     
     
       19. A coin detecting system comprising: at least two sensor units, each sensor unit including a body having spaced apart sides defining an air gap in said body and a flux return path in said body for magnetic flux from one of said sides to the other of said sides, said air gap having a width larger than the diameter of a coin in order to accommodate a coin in said air gap;   a positioning device for positioning a sample coin in said air gap of one of said sensor units and a test coin path through said air gap of another one of said sensor units;   an electronic control that is responsive to said magnetic flux in said at least two sensor units when a Sample coin is in said air gap of one of said sensor units and a test coin is in said test coin path, said electronic control including a plurality of induction devices, one magnetically coupled with each of said sensor units, an excitation generator for electrically exciting said induction devices in order to generate a magnetic flux in each sensor unit body from one of said sides to the other of said sides through said air gap; and   a detection system for comparing an electrical signal produced by said induction devices to determine if a test coin in said test coin path is the same as a sample coin in said positioning device, wherein said detection system includes a comparison circuit which produces an output indicative of the intensities of said electrical signals produced by said induction devices and a detection circuit responsive to said comparison circuit output, said detection circuit including a differential amplifier having an output, a first input connected with said output of said comparison circuit and a first reference voltage, a feedback path between said output and said first input and said reset input resets said detector circuit output to the other of said two output states, a second input connected with a second reference voltage and a reset input, whereby said feedback path latches said detection circuit output in one of two output states and said reset input resets said detector circuit output to the other of said two output states.   
     
     
       20. The system in claim 19 including a coin confirmation sensor connected with said reset input, said coin confirmation sensor responsive to a coin being deposited in a coin receptacle. 
     
     
       21. A coin detecting system comprising: at least two Sensor units, each sensor unit including a body having spaced apart sides defining an air gap in said body and a flux return path in said body for magnetic flux from one of said sides to the other of said sides, said air gap having a width larger than the diameter of a coin in order to accommodate a coin in said air gap;   a positioning device for positioning a sample coin in said air gap of one of said sensor units and a test coin path through said air gap of another one of said sensor units;   an electronic control that is responsive to said magnetic flux in said at least two sensor units when a sample coin is in said air gap of one of said sensor units and a test coin is in said test coin path, said electronic control including a plurality of induction devices, one magnetically coupled with each of said sensor units, an excitation generator for electrically exciting said induction devices in order to generate a magnetic flux in each sensor unit body from one of said sides to the other of said sides through said air gap; and   a detection system for comparing an electrical signal produced by said induction devices to determine if a test coin in said test coin path is the same as a sample coin in said positioning device, wherein said detection system includes a circuit responsive to said electrical signals produced by said induction devices and adapted to comparing the magnitude of said electrical signals when a test coin is in said test coin path, wherein said circuit has at least one natural resonance frequency, said excitation generator including a square wave generator generating a square wave having a fundamental frequency and a plurality of harmonic frequencies, said square wave including low-order harmonic frequencies and high-order harmonic frequencies, wherein said natural resonance frequency does not coincide with said fundamental frequency or one of said low-order harmonics frequencies.   
     
     
       22. The system in claim 21 wherein said low-order harmonics include a third-order harmonic and below. 
     
     
       23. A coin detecting system comprising: at least two sensor units, each sensor unit including a body having spaced apart sides defining an air gap in said body and a flux return path in said body for magnetic flux from one of said sides to the other of said sides, said air gap having a width larger than the diameter of a coin in order to accommodate a coin in said air gap, wherein said sides converge outwardly from a central portion of said body;   a positioning device for positioning a sample coin in said air gap of one of said sensor units and a test coin path through said air gap of another one of said sensor units;   an electronic control that is responsive to said magnetic flux in said at least two sensor units when a sample coin is in said air gap of one of said sensor units and a test coin is in said test coin path, said electronic control including a plurality of induction devices, one magnetically coupled with each of said sensor units, an excitation generator for electrically exciting said induction devices in order to generate a magnetic flux in each sensor unit body from one of said sides to the other of said sides through said air gap; and   a detection system for comparing an electrical signal produced by said induction devices to determine if a test coin in said test coin path is the same as a sample coin in said positioning device.